There is a growing demand in the drug discovery and related fields for high throughput cell culture systems, that is, systems capable of supporting large numbers of cell-culture assays in parallel. For a variety of reasons, it would be desirable to conduct large-scale cell-culture assays in a microfluidics device having an array or microwells and microfluidics structure for populating and feeding the wells. One major advantage of microfluidic cell culture is the possibility to mimic in vivo conditions. Culture parameters such as medium flow rate, shear stress, Peclet number, Reynolds number, liquid/cell volume ratio, length scale, and cell density can be controlled to more closely match physiologic conditions. Continuous medium perfusion and “on-chip” monitoring ensure a stable environment for cells during observation. These factors should limit variations in cell behavior and improve the statistical power of experiments. It is also likely that by providing more in vivo-like culture conditions, cell behavior will be closer to physiologic conditions, making assay results more relevant for medical applications.
The potential advantages of a microwell array device have been realized to a rather limited extent only in the prior art. Various limitations associated with prior art 30 devices include (i) the requirement for bulky robotics to populate the wells in the device, (ii) difficulty in preventing microfluidics structures from being blocked by cell growth within the structures, (iii) inability to sustain uniform culture conditions over an extended assay period, (iv) inability to achieve and alter cell-culture conditions at the level of individual wells, and (v) difficulty in creating the necessary microfluidics structures efficiently by microfabrication.
It would therefore be desirable to provide a microwell array device capable of more fully realizing the advantages noted above in a high throughput cell culture system. There is also a need to achieve these advantages in a microfluidics device that can be constructed efficiently by microfabrication.